Surgical Instrumentation Assembly for Positioning an Ankle Prosthesis

ABSTRACT

In order to position an ankle prosthesis including a tibial implant and a talus implant provided with a talo-calcaneal anchoring keel, the invention proposes a surgical instrumentation assembly including: a tibial phantom (60) of the tibial implant, adapted so as to be attached to the tibia (T) of a patient, and an aiming guide (80) adapted for setting into place an instrumentation element (90) through the talus (A) and the calcaneus (C) of the patient, along an axis (Z-Z) for implanting the talo-calcaneal anchoring keel, the tibial phantom and the aiming guide mechanically cooperating with each other to restrict movement of the tibial phantom and the aiming guide relative to each other along vertical and medio-lateral directions, wherein the aiming guide is configured to guide placement of the instrumentation element.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/734,876, filed on Jan. 6, 2020, which application is a divisionalapplication of and claims priority and benefit under 35 U.S.C. § 121 toU.S. patent application Ser. No. 15/400,557, filed on Jan. 6, 2017, nowissued as Ser. No. 10,524,935, which application is a continuationapplication of and claims priority and benefit under 35 U.S.C. § 120 toU.S. patent application Ser. No. 13/669,321, filed on Nov. 5, 2012, nowissued as U.S. Pat. No. 9,539,115, which claims priority and benefitunder 35 U.S.C. § 119(e) to U.S. Provisional Patent Application Ser. No.61/555,593, filed on Nov. 4, 2011, and claims foreign priority to FrenchPatent Application No. 1251091, filed on Feb. 6, 2012, which the entirecontents of the aforementioned applications are incorporated herein byreference in their entireties for all purposes.

TECHNICAL FIELD

The present invention relates to a surgical instrumentation assembly forpositioning an ankle prosthesis.

BACKGROUND OF THE INVENTION

Placement of an articular prosthesis at the ankle of a patient during asurgical operation, typically from an anterior approach path, requirespreparation notably by resections, of the lower end of the tibia, aswell as often the upper end of the talus of the patient, in order topermanently fix thereon the tibia and talus implants belonging to theankle prosthesis. In practice, once the bone preparations are carriedout, the surgeon frequently resorts to phantoms of prosthetic implants,allowing the surgeon to make sure that these preparations are suitableand that additional bone cutting or additional resurfacings are notnecessary. These phantoms are not necessarily of the same shape as thecorresponding implant.

Sometimes, a patient may be fitted with an initial fitted ankleprosthesis, and the initial implantation may be revised subsequently; inthe case of a revision, the talar implant is often provided with atalo-calcaneal anchoring keel, which may be sufficiently long forstabilizing the talus implant facing both the talus and the calcaneus ofthe patient. This being said, this type of ankle prosthesis with a longkeel may of course be positioned as a first intention prosthesis,notably if the bones of the foot are highly damaged. It is understoodthat the positioning instrumentation for an ankle prosthesis with a longkeel should allow the surgeon to prepare the talus and the calcaneusaccordingly, so that these bones are ready to receive the aforementionedlong keel in an ad hoc housing. Further, in spite of all the care whichthe surgeon may provide in handling such instrumentation, notably with asignificant intervention time, the risks are not negligible that thepreparation of the aforementioned housing might be not satisfactory, inthe sense that the implantation of the talus component resulting fromthis does not allow good subsequent articular cooperation with thetibial component attached to the tibia.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the present invention include a surgical instrumentationassembly for positioning an ankle prosthesis with a talus implantprovided with a talo-calcaneal anchoring keel, an instrumentationassembly which allows the surgeon to ensure satisfactory implantationpositioning between the tibial implant and the talus implant, notablyfor reasons of stability and longevity of the ankle prosthesis.

A surgical instrumentation assembly for positioning an ankle prosthesisaccording to embodiments of the present invention includes a tibiaimplant and a talus implant provided with a talo-calcaneal anchoringkeel, the instrumentation assembly including a tibial phantom of thetibial implant, adapted for attachment to the tibia of a patient, and anaiming guide, adapted for setting into place an instrumentation elementthrough the talus and the calcaneus of the patient along an axis forimplanting the talo-calcaneal anchoring keel, wherein the tibial phantomand the aiming guide mechanically cooperate with each other to restrictmovement of the tibial phantom and the aiming guide relative to eachother along vertical and medio-lateral directions, wherein the aimingguide is configured to guide placement of the instrumentation element.

According to some embodiments of the present invention, the tibialphantom and the aiming guide are mechanically coupled so that thevertical and medio-lateral positioning of the tibial phantom on thetibia correspondingly forces vertical and medio-lateral positioning ofthe aiming guide. In this way, the placement by the aiming guide of atalo-calcaneal instrumentation element such as a pin or the like, ispositioned relative to the tibial phantom when the latter is attached tothe tibia in the same configuration as the one in which the tibialimplant of the ankle prosthesis will then be attached. Once thisinstrumentation element is thus placed through the talus and thecalcaneus, it is intended to be used by the surgeon for preparing thetalus and the calcaneus to receive the anchoring keel of the talusimplant of the prosthesis, this preparation therefore being reliably andaccurately positioned with respect to the tibial phantom fixed to thetibia.

In practice, the aforementioned instrumentation element is placed by theaiming guide while the surgeon sets the ankle of the patient in apreferential configuration, notably by setting the foot at 90 degreeswith respect to the leg of the patient in the sagittal plane. Thus, theimplantation of this element and therefore the implantation of theanchoring keel of the talus implant are achieved by means of theinstrumentation according to embodiments of the invention, by takinginto account the implantation of the tibial implant and of theaforementioned preferential configuration of the ankle.

The subsequent articular performances of the thereby implanted ankleprosthesis are remarkable because of the satisfactory relativepositioning of the tibia and talus implants, this positioning beingeasily obtained rapidly by the surgeon during the positioning operationby the instrumentation according to embodiments of the presentinvention.

While multiple embodiments are disclosed, still other embodiments of thepresent invention will become apparent to those skilled in the art fromthe following detailed description, which shows and describesillustrative embodiments of the invention. Accordingly, the drawings anddetailed description are to be regarded as illustrative in nature andnot restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 to 3 illustrate an ankle prosthesis, FIG. 1 being an explodedperspective view and FIGS. 2 and 3 corresponding to elevational viewsalong the arrows II and III of FIG. 1 respectively.

FIG. 4 is a perspective view of the ankle of a patient illustrating afirst step for preparing this ankle with view to positioning of theprosthesis of FIGS. 1 to 3, this first preparation step being carriedout by a corresponding portion of an exemplary embodiment of aninstrumentation assembly according to embodiments of the presentinvention.

FIG. 5 is a view similar to FIG. 4, illustrating a second step forpreparing the ankle with a corresponding portion of the instrumentation,according to embodiments of the present invention.

FIG. 6 is a view similar to FIGS. 4 and 5, illustrating a third step forpreparing the ankle with a corresponding portion of the instrumentation,according to embodiments of the present invention.

FIGS. 7 to 9 are views similar to FIGS. 4 to 6, respectivelyillustrating successive movements of a fourth step for preparing theankle with corresponding portions of the instrumentation, according toembodiments of the present invention.

FIG. 10 is the same view as that of FIG. 9, with a partial sectionalview along the plane X indicated in FIG. 9, according to embodiments ofthe present invention.

FIGS. 11 to 13 are views similar to FIGS. 4 to 9, respectivelyillustrating the successive moments of a second step for preparing theankle with corresponding portions of the instrumentation, according toembodiments of the present invention.

FIG. 14 is a view similar to FIGS. 4 to 9 and 11 to 13, illustrating theimplantation of a prosthesis of FIGS. 1 to 3 at the ankle having beenprepared by the instrumentation, according to embodiments of the presentinvention.

FIGS. 15, 16 and 17 are views similar to FIGS. 7, 9 and 10 respectively,illustrating an alternative instrumentation according to embodiments ofthe present invention.

While the invention is amenable to various modifications and alternativeforms, specific embodiments have been shown by way of example in thedrawings and are described in detail below. The intention, however, isnot to limit the invention to the particular embodiments described. Onthe contrary, the invention is intended to cover all modifications,equivalents, and alternatives falling within the scope of the inventionas defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

In FIGS. 1 to 3, an example of an ankle prosthesis 1 is illustrated.This prosthesis includes three distinct components to be implanted atthe joint of an ankle of a human being, in this case, for the exampleconsidered in the figures, a right ankle of such a human being. Thesecomponents are a tibia implant 10, a talus implant 20 and a prostheticshoe 30.

For convenience, the following of the description is oriented relativelyto the bones of an ankle in their anatomic position, i.e. the term of“posterior” or “rear”, “anterior” or “front”, “right”, “left”, “upper”,“lower”, and the like, are understood with respect to the ankle of apatient standing on his/her feet on a substantially horizontal surface.Also the term of “sagittal” corresponds to a direction in theantero-posterior direction, vertically on the middle line of the ankle,while the “front plane” corresponds to a vertical plane perpendicular tothe sagittal plane of the ankle.

The tibial implant 10 includes a plate 11 to be attached to the lowerend of the right tibia of a patient, after suitable preparation of thisend. For this purpose, the plate 11 is, on its upper side, made in asame material with a bone anchoring sagittal stem 12 intended to becemented with respect to the tibia. As an alternative not shown, boneanchoring means, other than the sagittal stem 12, may be contemplatedfor the plate 11 from the moment that they efficiently immobilize thetibia implant 10 at the lower end of the tibia.

On its lower side, the plate 11 is secured to the upper face of the shoe30. In practice, various embodiments are contemplated with respect tothe securing interface, not visible in detail in the figures, eitherfixed or mobile, between the plate 11 and the shoe 30.

The talus implant 20 includes a main block 21 to be attached to theupper end of the right talus of a patient, for example through ananchoring keel 22 extending downwards from the lower side of the block21. The keel 22 has a significant longitudinal dimension, in the sensethat, in operation, the keel 22 is provided so as to continuously extendthrough the whole right talus of the patient and through at least oneportion of the right calcaneus of the patient. Further, as this is wellvisible in FIGS. 2 and 3, keel 22 extends from the lower side of theblock 21 with a specific tilt, related to the fact that the keel 22 isconfigured so as to extend into bone portions of greater bone mass andhigher stress resistance of the talus and of the calcaneus, notably withpurposes of stabilization of the keel towards the bones. The benefit ofthis arrangement is related to the fact that the talus of the patientmay, upon positioning of the implant 20, either be of a poor bonequality, or only be present in a small amount, or having been at leastpartly altered beforehand, in particular following the removal of atalus implant from a first-time fitted ankle prosthesis, implantedearlier in the patient to be operated, which moreover justifies in thelatter case that the prosthesis 1 be described in some embodiments as a“revised prosthesis”.

According to one embodiment of the present invention, the keel 22 has anessentially frusto-conical outer surface, centered on a geometrical axisY-Y which extends along the longitudinal direction of the keel 22 andwhich forms an axis for implantation of this keel in the talus and thecalcaneus. Also as a non-limiting example and independently of thefrusto-conical outer shape of the keel 22, the central longitudinal axisY-Y of this keel is inclined relatively to the normal to the lower sideof the main block 21, more generally relatively to a vertical anatomicdirection, by forming, in a sagittal plane like in FIG. 2, an angulationα and forming in a front plane like in FIG. 3, an angulation β. Theangulations α and β may have respective variable values, depending onthe anatomy of the patient: in particular, according to some embodimentsof the present invention, the angulation α has the value from about 40to 55 degrees and the angulation β has the value from about 0 to 15degrees.

On its upper side, the block 21 delimits an articular surface intendedto cooperate with a conjugate articular surface which is delimited onthe lower side of the shoe 30. In practice, the profile of theaforementioned articular surfaces is not a limitation of the presentinvention and will therefore not be further described: in any case, byarticular cooperation with the upper side of the block 21 and the lowerside of the shoe 30, the ankle prosthesis 1 advantageously provideskinematics close to those of the natural joint of the ankle.

A surgical method will be described hereafter, aiming at implanting theankle prosthesis 1, it being understood that the relevant prosthesis isonly a non-limiting illustrative example of the method and of thesurgical instruments used for implanting this prosthesis. In otherwords, the method and the instruments detailed hereafter may be used forimplanting ankle prostheses of very diverse structures, for example forwhich the tibia and/or talus implants consist of several parts assembledto each other, of metal, plastic and/or ceramic nature.

In a first operating step, which is illustrated in FIG. 4, the tibia Tbegins by being prepared at the right ankle of the patient. For thispurpose, the surgeon uses a first cutting block 40 which, in therelevant exemplary embodiment here, is attached onto the tibia T via apositioning guide 42: this positioning guide 42 is designed in order tobe fixedly pressed on the tibia T, notably on its epiphysis and/or itsanterior tuberosity, while allowing adjustment of at least certaincharacteristics of the positioning of the cutting block 40, supported bythe positioning guide 42, relatively to the tibia T. In particular, thepositioning guide 42 provides the possibility of adjusting the positionof the cutting block 40 along the longitudinal direction of the tibia Tand/or the angular position of the cutting block 40 around anantero-posterior axis and/or the position of the cutting block 40 alonga medio-lateral axis.

Alternatively, the positioning guide 42 described above may be replacedwith unadjustable means for immobilizing the cutting block 40 on thetibia T, typically in the form of one or several bone anchoring pins,directly and fixedly binding the cutting block and the bone material ofthe tibia, according to embodiments of the present invention.

The cutting block 40 delimits a slot 44 for accepting a bone cuttingmechanism, into which the surgeon introduces and guides for example acutting blade 46 so as to resect the lower end of the tibia T along acorresponding tibial cutting plane.

Before proceeding to the second operating step described and shown inFIG. 5, an optional intermediate step, not shown, includes resecting theupper end of the talus A of the ankle of the patient, by then forming acorresponding talus cutting plane. In particular, as a non-limitingexample, the tibial and talus cutting planes are substantially parallelto each other when the foot of the patient is positioned at 90 degreesrelative to the patient's leg. In practice, such resection of the talusA is often not necessary within the scope of a revision surgicaloperation in the sense that the bone preparation of the talus, which hadbeen carried out earlier with the purposes of implanting a first-timefitted ankle prosthesis, has already given rise to the making of such atalus cutting plane and is therefore generally sufficient forpositioning the ankle prosthesis 1. This having been said, if need be,the surgeon has the option of using a cutting blade or a similarmechanism for resecting the upper end of the talus A, for example byintroducing and guiding this cutting blade in the slot of a cuttingblock which is similar to the cutting block 40 described above and whichmay be borne by the positioning guide 42.

More generally, before proceeding to the second operating step describedhereafter with reference to FIG. 5, other secondary operations for bonepreparation of the lower end of the tibia T and/or of the upper end ofthe talus A may be carried out in order to have on these ends cuttingplanes suitable for positioning the ankle prosthesis 1. For example,such additional steps may include the elimination, on the bone surfacescorresponding to these cutting planes, of possible osteophytes orresidual materials.

In a second operating step, illustrated in FIG. 5, a window may be madein the anterior face of the tibia. To do this, the surgeon uses a secondcutting block 50 which the surgeon immobilizes on the tibia T, notablywith pins 51 introduced into the tibia along a globally antero-posteriordirection. This block 50 delimits two slots 52, which extend parallelwith each other along a vertical direction and into each of which thesurgeon introduces a bone cutting mechanism, in this case a cuttingblade 53 as shown in FIG. 5, so as to cut into the bone material of thetibia T, two substantially vertical grooves, which open only onto theanterior face of the tibia, according to embodiments of the presentinvention.

In practice, before immobilizing the block 50 on the tibia T with thepins 51, the surgeon carefully positions this block 50 so that bothgrooves made in the tibia extend parallel to the longitudinal directionof the tibia T. To do this, as an example, a localizing element 54 isprovided on the cutting block 50 so that this localizing element 54 isaligned on the tibial crest in the front plane relative to the angle,while being parallel with this crest in a sagittal plane, when thecutting block is suitably positioned relative to the tibia.Additionally, the cutting block 51 may be provided with a palette 55designed so as to be flattened upwards against the tibial cutting plane.Such palette 55 may protrude on the rear face of the cutting block 51,according to embodiments of the present invention.

At the end of the second operating step, the cutting block 50 isdisengaged and, with an osteotome, in particular a Poirier osteotome,the segment of bone material subsisting between both grooves made in theanterior face of the tibia T may be detached from the remainder of thetibia, thereby clearing a window through the tibia T. As shown in FIG.6, the aforementioned tibial window opens both onto the anterior face ofthe tibia and onto the tibial sectional plane. If need be, the wallsdelimiting the aforementioned tibial window are reworked, for examplewith rasps provided for this purpose.

In a third operating step, shown in FIG. 6, a test tibial implant, inother words a tibial phantom 60 of the tibial implant 10, may be setinto place on the tibia T. This tibial phantom 60 includes a main plate61, which has a peripheral contour geometrically similar to that of theplate 11 of the tibial implant 10 and for which the upper side has thesame arrangement as that of the plate 11, i.e. the plate 61 is providedwith a protruding sagittal stem 62 geometrically similar to the stem 12of the tibial implant 10. Further, the stem 62 of the tibial phantom 60delimits through-holes 63 for receiving a pin for attachment to thetibia. On its lower side, the plate 61 has a planar surface which, asindicated in dotted lines in FIG. 6, and as partly visible in FIGS. 7and 10, is provided with,—in the central region of this lower planarsurface, a protruding bulge 64 which, in the relevant exemplaryembodiment shown, is made in the same material with the remainder of theplate 61; and each of the opposite, medial and lateral edges of thislower planar surface, a slide 65, which extends along anantero-posterior direction from the front end of the plate 61 towardsthe rear end of the latter and which, in the relevant exemplaryembodiment here, has an overall U profile, the respective recesses ofthe U profiles of both slides 65 being directed towards each other alonga medio-lateral direction.

In order to set into place the tibial phantom 60, the surgeonmanipulates it with a grip 70, the distal end of which is adapted to beremovably attached to a dedicated area of the tibial phantom 60, thisarea being located, in one non-limiting example, at the base of theanterior side of the stem 62. It is understood that by displacing thegrip 70, the surgeon is thus able to insert the tibial phantom 60 intothe ankle joint of the patient via an anterior route, more specificallyby inserting the stem 62 into the inside of the aforementioned tibialwindow, while flattening the upper face of the plate 61 against thelower sectional plane of the tibia T.

In practice, the surgeon adjusts the antero-posterior position of thetibial phantom 60 relative to the tibia T by correspondingly displacingthe grip 70 while, along the vertical direction, the surgeon makes surethat the plate 61 is maintained pressed upwards against the lowersectional plane of the tibia T. The surgeon may be assisted for this byretractors or similar equipment, according to embodiments of the presentinvention.

Once the surgeon decides that the tibial phantom 60 is properlypositioned on the tibia T, the surgeon fixes it into position with pins71 introduced through the lower end of the tibia T, by passing each pinthrough one of the through-holes 63 of the stem 62. Advantageously, theinsertion of these pins 71 is guided by an aiming guide 72, which isborne by the grip 70 and which bears a piercing barrel 73 for guidingeach pin 71 along the respective central axis of the through-holes 63.

Once the tibial phantom 60 is attached on the tibia T by the pins 71,the grip 70 and the aiming guide 72 are disengaged therefrom.

As an option, a control with an image intensifier may then be appliedfor confirming the proper positioning of the tibial phantom 60 withrespect to the tibia T.

In a fourth operating step, which is illustrated by FIGS. 7 to 10, thetalus A and the calcaneus C may be prepared with view to positioning theimplantation of the talo-calcaneal keel 22 of the talus implant 20. Todo this, the surgeon uses an aiming guide 80 which, as well visible inFIGS. 7 and 10, includes a main body 81, as well as a piercing barrel 82which delimits a bore 83 for letting through a pin and which isremovably borne by the body 81. The body 81 of the aiming guide 80 isdimensioned so as to be received in an interposed way, along thevertical, between the plate 61 of the tibial phantom 60 attached to thetibia T and the upper sectional plane of the talus A, as shown in FIG.8. More specifically, the upper side of the main body 81 is provided, oneach of these opposite, medial and lateral edges, with a slider 84 whichextends along an antero-posterior direction. These sliders 84 areadapted so as to be respectively engaged complementarily into the slides65 of the tibial phantom 60 so as to reversibly assemble the tibialphantom 60 and the aiming guide 80 according to an antero-posteriorsliding link.

The slides 65 and the sliders 84 are dimensioned, to within functionaltolerances, in order to limit, or even make substantially zero therelative displacements between the tibial phantom 60 and the aimingguide 80 along both the vertical direction and the medio-lateraldirection. In other words, the antero-posterior sliding link between thetibial phantom 60 and the aiming guide 80 represents the only degree offreedom of displacement between these components. In other words, thevertical and medio-lateral positioning of the tibial phantom 60 on thetibia T accurately constrains or restricts the vertical andmedio-lateral positioning of the aiming guide 80.

Further, as partly illustrated in dashed lines in FIG. 7 and as shown inFIG. 10, the main body 81 of the aiming guide 80 delimits, in its medianregion, a slot 85, which is open on the outside while opening both ontothe opposite, upper and lower faces of the body 81 and on the rear faceof the body 81, while the slot 85 is closed at the front face of thebody 81 by a front wall of this body. Slot 85 is arranged so as toremovably attach thereto the piercing barrel 82 so that the bore 83 ofthe latter opens downwardly into the inside of the slot 85. Thus, asshown in FIG. 10, the central longitudinal axis of the bore 83 crossesthe body 81 while extending into the inside of the slot 85, by goingfrom the lower end of the piercing barrel 82 as far as the lower face ofthe main body 81. The plane of FIG. 10, which corresponds to the planenoted as X in FIG. 9, is a plane containing the central axis of the bore83 and parallel to the sliding direction of the sliding link between thetibial phantom 60 and the aiming guide 80, this plane forming a middleplane, notably a plane of symmetry for the slot 85, according toembodiments of the present invention.

Within the scope of the method for positioning the ankle prosthesis 1,the aiming guide 80 is manipulated by a surgeon, if necessary, via agrip (not shown), such that the body 81 of the aiming guide is insertedunder the tibial phantom 60, by sliding the aiming guide 80 against thetibial phantom by engagement of the sliders 84 with the slides 65, asindicated by the arrow 86 in FIG. 7. The slid position of the aimingguide 80 relative to the tibial phantom 60, in other words the relativeantero-posterior positioning between the aiming guide and the tibialphantom, is adjusted by the surgeon. Accordingly, several approaches maybe used. Indeed, this adjustment may be left to the entire discretion ofthe surgeon. According to some embodiments of the present invention,preferential or extreme positioning is advantageously provided to thesurgeon, by abutment, along the antero-posterior direction, between thebulge 64 of the plate 61 of the tibial phantom 60 and the main body 81of the aiming guide 80, this body 81 delimiting a housing 87 forcomplementary reception of the bulge 64. For example, FIGS. 8 to 10illustrate the abutment of the bulge 64 in this housing 87, according toembodiments of the present invention.

In any case, once the relative positioning between the aiming guide 80and the tibial phantom 60 is adjusted according to the desire of thesurgeon, and while maintaining the foot of the patient at 90 degreesrelative to the patient's leg, the surgeon introduces a pin 90 into thepiercing barrel 82, this pin being driven towards the rear of the foot,while being guided by the bore 83 in a centered way on the axis of thelatter, successively through the slot 85, through the whole talus A andthrough at least one portion, or even the totality of the calcaneus C,as illustrated in FIGS. 9 and 10. As explained below, thistalo-calcaneal pin 90 determines the implantation positioning of thetalus implant 20, for example by determining an implantation axis Z-Z ofthe keel 22 of the talus implant 20.

As an option, just before putting the pin 90 into place, the aimingguide 80 may be used by the surgeon for checking and if necessary,adjusting the alignment of the joint of the ankle while the foot of thepatient is maintained at 90 degrees relative to the patient's leg. To dothis, the aiming guide 80 is provided with a predetermined raisedportion or localization mark of the position of the aiming guide 80 withrespect to at least one anatomic singularity of the talus A, such as thetalonavicular joint. Moreover, in FIG. 8, the main body 81 bears as anadvantageous optional arrangement such a raised localization portion 88on which the surgeon may align the talonavicular joint of the foot. Thelocalization portion 88 may also be referred to as a visual indicator88, according to embodiments of the present invention.

At the end of this fourth operating step, while the pin 90 is left inplace through the talus A and the calcaneus C, and while the tibialphantom 60 is left in place on the tibia T, the surgeon totallydisengages the aiming guide 80. More specifically, the surgeon detachesthe piercing barrel 82 relative to the main body 81 and has thispiercing barrel slide along the pin 90 towards the front end of thelatter, until it is removed from the pin. Next, the surgeon has the mainbody 81 slide forwards (i.e. anteriorly) with respect to the tibialphantom 60: the benefit of the presence of the slot 85 is thusunderstood as permitting disengagement of the main body 81 without themain body 81 interfering with the pin 90 left in place, this slot 85being dimensioned accordingly, notably with respect to its tilt relativeto the upper and lower faces of the main body 81, as well as withrespect to its medio-lateral width, according to embodiments of thepresent invention.

In a fifth operating step illustrated by FIGS. 11 to 13, the talus A andthe calcaneus C may be pierced in order to produce in these bones areceiving housing mating the keel 22 of the talus implant 20. To dothis, as illustrated in FIG. 11, a test talus component, in other wordsa talus phantom 100, is set into place in an interposed way between thetibial phantom 60 and the talus A. This talus phantom 100 includes amain block 101 delimiting a lower planar surface which has a peripheralcontour geometrically similar to that of the lower surface of the mainblock 21 of the talus implant 20. The block 101 may be set into place onthe talus A, by flattening it against the upper sectional plane of thistalus, in other words in a configuration similar to the one which thetalus implant 20 will occupy at the end of the intervention.

The talus phantom 100 may thus set into place while the pin 90 is leftin place through the talus A and the calcaneus C. Therefore, the mainblock 101 is provided with a through-hole 102, which connects the upperand lower sides of the block 101 and inside which the pin 90 is axiallyengaged. In other words, the talus phantom 100 is slid over the pin 90until it flattens the lower face of its main bulk 101 against thesectional plane of the talus A. Some freedom of tilt of the main block101 relative to the pin 90 may be left, which accounts for why thediameter of the through-hole 102 is significantly larger than theexternal diameter of the pin 90. This arrangement may benefit from thesurgeon's use of a centering device 110, which, as illustrated in FIG.12, may be slid over the pin 90 while being adjusted on the outerdiameter of the latter, until it is laid out, by adjustment in aradially interposed way between the pin 90 and the main block 101, atthe through-hole 102 of the latter. Once the centering device 110occupies the through-hole 102, the positioning of the talus phantom 100is constrained specifically with respect to the pin 90, with the block101 of this phantom being held downwards bearing against the uppersectional plane of the talus. The position of the talus phantom 100 maythen be set with respect to the talus, by attaching the main block 101with two added pins (not shown) introduced into dedicated through-holes103 of the main block 101.

As an alternative (not shown), the through-hole 102 opens onto the frontof the block 101, which forms an open slot at one end to facilitate thesetting into place of the pin 90 in this slot, in the sense that at anyintermediate level of the pin, the pin may be laterally engaged into theaforementioned slot. Unless the width of the aforementioned slot islimited to the diameter of the pin 90, which may prove to be aconstraint in terms of preoperative manipulations, the subsequent use ofthe centering device 110 remains relevant, according to embodiments ofthe present invention.

As an option, before continuing the progression to the fifth operatingstep, a control with an image intensifier may be used to confirm theproper alignment of the tibial 60 and talus 100 phantoms.

After having removed the centering device 100 by backing it out alongthe pin 90, according to a reverse procedure relative to its initialinstallation, the talus A and the calcaneus C are pierced (e.g. drilled,reamed, and the like) in order to produce in these bones a matingreceiving housing for the keel 22 of the talus implant 20. This piercingmay be achieved with the pin 90 left in place through the talus A andthe calcaneus C, by using the pin 90 as a guiding support along which isslid at least one bone piercing tool 120, such as a cannulated millingtool or a reamer, as illustrated in FIG. 13. Moreover, several of thesepiercing tools may be used successively for widening and/or reworkingthe shape of the successive bone cavity. In each case, the main block101 may form an abutment, along the longitudinal direction of the pin90, for these piercing tool(s) 120: in this way, the centrallongitudinal axis of the pin 90 determines the central axis Z-Z aroundwhich is made the cavity for receiving the anchoring keel 22, while theabutment of the piercing tool(s) 120 against the talus phantom 100determines the depth of this cavity.

At this stage of the surgical operation, the tibia T, the talus A andthe calcaneus C are ready to receive the tibia 10 and talus 20 implantsof the prosthesis 1, as described hereafter with reference to FIG. 14.Optionally, before setting these implants 10 and 20 into place, testsmay be conducted by the surgeon with the tibial phantom 60, the talusphantom 100 and one or several phantoms, not shown, of the shoe 30 foradjusting the vertical spacing between the lower end of the tibia T andthe upper end of the talus A and thereby re-establishing anatomicalseparation between them, as well as with test rods, not shown, passedthrough the main block 101, via the through-hole 102, in order to checkthe proper depth of the housing made through the talus and thecalcaneus. Once these tests are completed, the pin 90, as well as thepin 71 are removed and the phantoms 60 and 100 are cleared.

The surgical operation ends with the setting into place of the tibia 10and talus 20 implants, as illustrated in FIG. 14. In particular, thetalus implant 20 is mounted on a specific grip, not shown, in order tobe put into place on the talus A, by engaging its keel 22 into thehousing made through the talus A and the calcaneus C and by aligning itsaxis Y-Y on the axis Z-Z for implanting it along this axis. Next, thetibia implant 10, on which the prosthetic shoe 30 has been attachedbeforehand, is, for example via a specific grip, not shown, set into theplace on the tibia T, by occupying the same configuration for attachmentto the tibia which was occupied by the tibia phantom 60.

In FIGS. 15 to 17, an alternative of the surgical instrumentation isillustrated, which is only distinguished from the aforementionedinstrumentation by its aiming guide, referenced as 80′. Morespecifically, as can be seen by comparing FIGS. 15, 16 and 17 with FIGS.7, 9 and 10, the aiming guide 80′ is identical with the aiming guide 80,except with respect to the lower side of its main body 81′. Also, inFIGS. 15 to 17, the components identical with the ones shown in FIGS. 7,9 and 10 bear the same numerical references and will not be describedhere in more detail, as they are already described above.

Thus, unlike the body 81 of the aiming guide 80, which, on its lowerside, delimits a substantially planar lower face 81A oriented along anantero-posterior direction, the body 81′ of the aiming guide 80′ has, onits lower side, a lower face 81A′ with a globally beveled shape: in theexemplary embodiment considered in FIGS. 15 to 17, this lower face 81A′includes a posterior portion 81A′.1, which is substantially planar andoriented along an antero-posterior direction as well as anterior portion81A′.2 which is substantially planar and which connects, in a tilted wayrelative to the antero-posterior direction, the posterior portion 81A′.1and the anterior face of the body 81′. This difference in shape of thelower faces 81A and 81A′ of the bodies 81 and 81′ is related toconsiderations relating to the bone condition in which the talus A isfound. Indeed, as explained above, the use of the aiming guide 80assumes the presence of an upper sectional plane of the talus A, thisupper sectional plane being either pre-existent in the setting intoplace of the ankle prosthesis 1, or specifically made by the surgeon atthe beginning of the surgical operation aiming at implanting this ankleprosthesis 1. During the surgical operation, the surgeon easily causescooperation by a plane-plane contact, of the aforementioned uppersectional plane of the talus A and of the lower face 81A of the body 81of the aiming guide 80, notably with the purposes of adjusting theirrelative position, in particular during the placement of thetalo-calcaneal pin 90. In the case when the talus A has an alterationsuch that making such an upper sectional plane is made impossible,notably from the fact of a necrosis or damage of the talus, the bonepreparation of the talus is then performed by the surgeon at an anatomiclevel located closer to the calcaneus C, at the very least for theposterior portion of the talus, while the anterior portion of the talusis generally restored by a bone graft. The posterior portion 81A′.1 ofthe lower face 81A′ of the body 81′ of the aiming guide 80′ may becaused to cooperate, along a plane-plane contact, with the residual rearportion of the talus A, or even directly with the calcaneus C in thecase when the rear portion of the talus A is totally removed by thesurgeon on the one hand and, the anterior portion 81A′.2 of this lowerface 81A′ may then be used by the surgeon for cooperating with theaforementioned bone graft, if necessary by having it rest against thisgraft so as to stabilize it, according to embodiments of the presentinvention.

Of course, for the embodiment of the instrumentation illustrated byFIGS. 15 to 17, the corresponding talus phantom, not shown in thesefigures, has its main block with a lower face geometrically similar tothe lower face 81A′ of the body 81′, according to embodiments of thepresent invention.

More generally, as yet another alternative (not shown), the geometry ofthe lower faces of the body of the aiming guide and of the body of thetalus phantom may be adapted to a particular bone preparation of thetalus A, taking into account the condition of the bone material of thelatter.

Various arrangements and alternatives to the surgical instrumentationdescribed herein as well as to the method for using this instrumentationmay moreover be used, either individually or in combinations of two ormore. For example, embodiments other than the sliding link are possiblefor the mechanical link between the tibial phantom 60 and the aimingguide 80 or 80′ from the moment that this mechanical link predeterminesthe relative positioning of the aiming guide and of the tibial phantomwhen the latter is attached to the tibia. Also, for example, afterhaving set the pin 90 into place, in other words after the fourthoperating step as described above, the surgeon may for various reasonswish to continue the operation by shifting the axis, along which theanchoring keel 22 of the talus implant 20 will be implanted at the endof the operation. To do this, the instrumentation includes an ad hocshifting part, in the form of a block crossed by at least two holesparallel to each other; this shifting part is added onto the alreadyimplanted pin 90, by engaging the latter into one of the twoaforementioned holes, while the other hole is then used by the surgeonfor setting into place a second talo-calcaneal pin, similar to the pin90; it is understood that this other talo-calcaneal pin then extendsparallel to the pin 90, while being shifted relatively to the latter bythe predetermined center line between both holes of the shifting part;as an extension of the foregoing considerations, an embodiment of thisshifting part may include a barrel including several through-holes,structurally and functionally similar to the two aforementioned holesand distributed in a predetermined way relatively to each other. As yetanother example, rather than using the pin 90, other functionallysimilar instrumentation elements may be used.

Various modifications and additions can be made to the exemplaryembodiments discussed without departing from the scope of the presentinvention. For example, while the embodiments described above refer toparticular features, the scope of this invention also includesembodiments having different combinations of features and embodimentsthat do not include all of the described features. Accordingly, thescope of the present invention is intended to embrace all suchalternatives, modifications, and variations as fall within the scope ofthe claims, together with all equivalents thereof.

1. A surgical instrumentation assembly for positioning an ankleprosthesis, the ankle prosthesis including a tibia implant and a talusimplant provided with a talo-calcaneal anchoring keel, theinstrumentation assembly comprising: a tibial phantom adapted forattachment to the tibia of a patient, and an aiming guide, adapted forsetting into place an instrumentation element through the talus and thecalcaneus of the patient along an axis for implanting the talo-calcanealanchoring keel, wherein the tibial phantom and the aiming guidemechanically engage with each other to allow movement of the aimingguide with respect to the tibial phantom along an anterior-posteriordirection and to restrict movement of the tibial phantom and the aimingguide relative to each other along vertical and medio-lateraldirections, wherein the aiming guide is configured to guide placement ofthe instrumentation element.
 2. The surgical instrumentation assembly ofclaim 1, wherein the aiming guide defines a through-passage forreceiving the instrumentation element, the through-passage positioned toclear the aiming guide with respect to the tibial phantom attached tothe tibia while leaving the instrumentation element in place through thetalus and the calcaneus.
 3. The surgical instrumentation assemblyaccording to claim 2, wherein the aiming guide comprises: a main body,which defines the through-passage, and a piercing barrel removablyattached to the main body while opening into the through-passage, thepiercing barrel adapted for guiding the instrumentation element alongthe axis for implanting the talo-calcaneal anchoring keel.
 4. Thesurgical instrumentation assembly of claim 3, wherein thethrough-passage is a slot which opens onto two opposing faces of themain body along a longitudinal direction of the instrumentation elementand onto at least one other face of the main body, so as to permitdisengagement of the aiming guide from the tibial phantom while leavingthe instrumentation element in place.
 5. The surgical instrumentationassembly of claim 1, wherein the tibial phantom and the aiming guidemechanically engage with each other in a manner permitting reversibleassembly via sliding along he antero-posterior direction.
 6. Thesurgical instrumentation assembly of claim 5, further comprising anabutment mechanism configured to stop the sliding along theantero-posterior direction of the aiming guide with respect to thetibial phantom.
 7. The surgical instrumentation assembly of claim 1,wherein the aiming guide comprises a visual indicator configured tofacilitate positioning of the aiming guide relative to a specificanatomic location of the talus.
 8. The surgical instrumentation of claim7, wherein the specific anatomic location of the talus is thetalonavicular joint.
 9. The surgical instrumentation assembly of claim1, further comprising a talus phantom, which, while the instrumentationelement extends through the talus and the calcaneus, is adapted forbeing engaged on the instrumentation element up to a position at whichthe talus phantom bears against the talus, a position in which the talusphantom is adapted so as to form an abutment, along the axis forimplanting the talo-calcaneal anchoring keel, for a tool for forming,into the talus and the calcaneus, a housing for receiving thetalo-calcaneal anchoring keel, centered on the implantation axis. 10.The surgical instrumentation assembly of claim 9, further comprising acentering device which is adapted so as to be added around theinstrumentation element, while being radially interposed between theinstrumentation element, in place through the talus and the calcaneus,and the talus phantom in its position bearing against the talus.
 11. Thesurgical instrumentation assembly of claim 1, further comprising amechanism for resecting a lower end of the tibia, the mechanism beingadapted for adjusting a position with respect to the tibia of acorresponding tibial sectional plane.
 12. The surgical instrumentationassembly of claim 11, wherein the mechanism is a first mechanism, thesurgical instrumentation assembly further comprising a second mechanismfor setting into place and attaching the tibial phantom on the tibia,the second mechanism adapted for flattening at least one dedicatedportion of the tibial phantom against the tibial sectional plane.